1. Field of the Invention
The present invention relates to high-frequency modules and mobile communication apparatuses including high-frequency modules, and more particularly, to a high-frequency module which can be shared by three different communication systems and a mobile communication apparatus including such a high-frequency module.
2. Description of the Related Art
A triple-band portable telephone has been proposed which can operate in a plurality of frequency bands, such as those in a digital cellular system (DCS) using the 1.8 GHz band, a personal communication service (PCS) using the 1.9 GHz band, and a global system for mobile communications (GSM) using the 900 MHz, as a mobile communication apparatus.
FIG. 12 is a block diagram of a front-end section of a general triple-band portable telephone. FIG. 12 shows a case in which first to third communication systems having frequencies that are different from each other are set to the DCS using the 1.8 GHz, the PCS using the 1.9 GHz, and the GSM using the 900 MHz.
The front-end section of the triple-band portable telephone is provided with an antenna 1, a diplexer 2, first to third high-frequency switches 3a to 3c, first and second LC filters 4a and 4b, and first to third SAW filters 5a to 5c. The diplexer 2 couples a transmission signal sent from one of the DCS, the PCS, and the GSM with the antenna 1 during transmission, and distributes a receiving signal sent from the antenna 1 to one of the DCS, the PCS, and the GSM during receiving. The first high-frequency switch 3a switches between the transmission-section side of the DCS and the PCS, and the receiving-section side of the DCS and the PCS. The second high-frequency switch 3b switches between the receiving section Rxd side of the DCS and the receiving section Rxp side of the PCS. The third high-frequency switch 3c switches between the transmission-section Txg side and the receiving section Rxg side of the GSM. The first LC filter 4a passes transmission signals for the DCS and the PCS and attenuates the harmonics of the transmission signals. The second LC filter 4b passes a transmission signal for the GSM and attenuates the harmonics of the transmission signal. The first SAW filter 5a passes a receiving signal for the DCS and attenuates the harmonics of the receiving signal. The second SAW filter 5b passes a receiving signal for the PCS and attenuates the harmonics of the receiving signal. The third SAW filter 5c passes a receiving signal for the GSM and attenuates the harmonics of the receiving signal.
The operation of the triple-band portable telephone will be described for the DCS first. During transmission, the first high-frequency switch 3a turns on the transmission section Txdp side to send a transmission signal that was sent from the transmission section Txdp and that has passed through the first LC filter 4a, to the diplexer 2, the diplexer 2 performs coupling, and then the signal is sent from the antenna 1. During receiving, a receiving signal received by the antenna 1 is distributed by the diplexer 2, the receiving signal sent from the antenna 1 is sent to the first switch 3a, which is located on the DCS and PCS side, the first high-frequency switch 3a turns on the receiving section side to send the signal to the second high-frequency switch 3b, and the second high-frequency switch 3b turns on the receiving section Rxd side of the DCS to send the signal to the receiving section Rxd of the DCS through the first SAW filter 5a. A similar operation is also performed for transmission and receiving for the PCS.
A case in which the GSM is used will be described next. During transmission, the third high-frequency switch 3c turns on the transmission section Txg side to send a transmission signal which was sent from the transmission section Txg and has passed the second LC filter 4b, to the diplexer 2, the diplexer 2 performs coupling, and the signal is sent from the antenna 1. During receiving, a receiving signal received by the antenna 1 is distributed by the diplexer 2, the receiving signal sent from the antenna 1 is sent to the third high-frequency switch 3c, and the third high-frequency switch 3c turns on the receiving section Rxg side to send the signal to the receiving section Rxg of the GSM through the third SAW filter 5c. 
Since the triple-band portable telephone, which is one of the conventional mobile communication apparatuses, uses three high-frequency switches, at least six diodes constituting the high-frequency switches are required. As a result, the triple-band portable telephone uses a very large amount of power, and a battery mounted to the triple-band portable telephone can be used only for a short period. Also, the operation of each diode is controlled in many operation modes, and thus, a complicated circuit is required.
In order to overcome the problems described above, preferred embodiments of the present invention provide a high-frequency module having a low power consumption and a compact circuit, and a mobile communication apparatus including such a high-frequency module.
According to a preferred embodiment of the present invention, a high-frequency module includes integrated front-end sections of first to third communication systems having frequencies that are different from each other, the high-frequency module includes a diplexer arranged to couple a transmission signal sent from any of the first to third communication systems to an antenna during transmission and arranged to distribute a receiving signal sent from the antenna to any of the first to third communication systems during receiving, a first high-frequency switch arranged to separate a transmission section for the first and second communication systems and receiving sections for the first and second communication systems, a SAW duplexer arranged to separate a receiving section for the first communication system and a receiving section for the second communication system, and a second high-frequency switch arranged to separate a transmission section and a receiving section for the third communication system.
The high-frequency module may further include at least one of a first filter arranged to pass a transmission signal sent from the first and second communication systems, a second filter arranged to pass a transmission signal sent from the third communication system, and a third filter arranged to pass a receiving signal for the third communication system.
In the high-frequency module, the SAW duplexer may include a SAW filter and a phase conversion component connected to the SAW filter.
According to another preferred embodiment of the present invention, a high-frequency module includes front-end sections of first to third communication systems having frequencies that are different from each other, the front-end sections including a diplexer arranged to couple a transmission signal sent from any of the first to third communication systems to an antenna during transmission and arranged to distribute a receiving signal sent from the antenna to any of the first to third communication systems during receiving, a first high-frequency switch arranged to separate a transmission section for the first and second communication systems and receiving sections for the first and second communication systems, a SAW duplexer arranged to separate a receiving section for the first communication system and a receiving section for the second communication system, and a second high-frequency switch arranged to separate a transmission section and a receiving section for the third communication system, wherein the diplexer, the first and second high-frequency switches, and the SAW duplexer are integrated in a laminated member including a plurality of laminated sheet layers.
The high-frequency module may be configured such that all elements of the diplexer and a portion of the elements of the first and second high-frequency switches and the SAW duplexer are built in the laminated member, and the remaining elements of the first and second high-frequency switches and the SAW duplexer are mounted on the laminated member.
According to a high-frequency module of various preferred embodiments of the present invention, since a diplexer, first and second high-frequency switches, and an SAW duplexer are provided, and the SAW duplexer separates a receiving section for a first communication system and a receiving section for a second communication system, the number of high-frequency switches is reduced. As a result, the number of diodes used is reduced, and the power consumption of the high-frequency modules is greatly reduced. This means that a low-power-consumption, high-frequency module is provided. In addition, a current is not required during the signal receiving operation.
Since the diplexer, the first and second high-frequency switches, and the SAW duplexer, which constitute the high-frequency module, are integrated into a laminated member obtained by laminating a plurality of sheet layers preferably formed of ceramic, the matching characteristic, the attenuation characteristic, or the isolation characteristic of each component is obtained. Therefore, a matching circuit is not required between the diplexer and the first and second high-frequency switches, or between the first high-frequency switch and the SAW duplexer. Consequently, the high-frequency module becomes much more compact than conventional devices.
The diplexer preferably includes inductors and capacitors. The first and second high-frequency switches preferably include diodes, inductors, and capacitors. The SAW duplexer preferably includes SAW filters and transmission lines. The first and second LC filters preferably include inductors and capacitors. These elements are built in, or mounted on a laminated member and are connected by connections disposed inside of the laminated member. Therefore, the high-frequency module is constituted by a single laminated member and is very compact. In addition, loss caused by wirings for connecting components is greatly reduced, and as a result, the loss of the entire high-frequency module is greatly reduced.
Since the lengths of the inductors and the transmission lines built in the laminated member are reduced by a wavelength reduction effect, the insertion losses of these inductors and the transmission lines are greatly reduced. Therefore, a compact and low-loss high-frequency module is provided.
According to another preferred embodiment of the present invention, a mobile communication apparatus includes a high-frequency module according to one of the preferred embodiments described above, which high-frequency module defines the front-end sections of the first to third communication systems, receiving sections for the first to third communication systems, and transmission sections for the first to third communication systems.
According to a mobile communication apparatus of a preferred embodiment of the present invention, since a front-end section defined by a high-frequency module which allows power consumption to be reduced is provided, the power consumption of the mobile communication apparatus itself can also be reduced.
According to a mobile communication apparatus of various preferred embodiments of the present invention, since a high-frequency module used can reduce power consumption and does not require a current during receiving, the mobile communication apparatus having this high-frequency module can have low power consumption and does not require any current when waiting for a call. As a result, a battery mounted in the mobile communication apparatus can be used for a much longer period than in conventional devices.
In addition, since the compact and low-loss high-frequency module is used, the mobile communication apparatus having this high-frequency module is made compact and has a high performance.
Other features, elements, characteristics and advantages of the present invention will become more apparent from the following detailed description of preferred embodiments of the present invention with reference to the attached drawings.